KR20230001007A - Method and setup for detecting surface haze of materials - Google Patents

Abstract

The present invention relates to a preliminary inspection performed on a material to identify that the material is free from visible surface defects; and a method for detecting the surface haze of a material, comprising surface haze inspection, to detect the surface haze of the material, wherein the optical filter module is configured in an optical path to the detector to avoid a photoluminescent signal being detected by the detector. It is configured in a surface haze inspection setup to filter the photoluminescent signal of the material. The present invention further provides a setup for detecting the surface haze of a material. Using the surface haze detection method and setup of the present invention, the surface haze value and/or material distribution can be accurately obtained.

Description

Method and setup for detecting surface haze of materials

The present invention relates to the field of material detection. More specifically, the present invention relates to a method and setup for detecting the surface of a material, and more particularly to a method and setup for detecting surface haze of a material.

With the development of science and technology, surface smoothness of materials (semiconductor wafers, glass or ceramics, etc.) is highly demanded in some fields. For example, in the fields of electronics and communications, the requirements for the surface quality of semiconductor wafers have become increasingly stringent. Since the creation of electronic components in the 1950's, semiconductor materials have been widely used in modern production and in our daily life, and their importance is obvious. BACKGROUND OF THE INVENTION [0002] With the continued miniaturization and integration of semiconductor devices, the surface condition of a substrate has an increasingly large influence on the properties of the device. In particular, higher surface roughness of the substrates will affect the carrier mobility, thereby resulting in less mobility and excessively longer delays. In addition, higher surface roughness of the substrate will also increase the recombination velocity of carriers on the surface, thus resulting in a shorter non-equilibrium carrier lifetime and poor performance of the device. Clearly, good substrate surface conditions are important for the peak performance of electronic devices.

"Surface haze" (or "haze") on the surface of a material refers to the surface morphology (i.e., micro-roughness) of materials (e.g., wafers) and the high concentration on or on the surface. Refers to non-directional light scattering caused by nearby imperfections. Generally, "surface haze" is used to characterize the quality of inhomogeneity on the scale below the detection limit of surface particle size. During the manufacturing process of certain materials with smooth surfaces (such as substrates), surface haze will be unavoidable. Surface haze is caused by the surface micro-roughness of the material, and will directly affect the performance of the material, for example, will damage the epitaxial quality of the substrate, which in turn will affect the resulting epitaxial will affect the quality of the taxial layer and device. Therefore, during manufacturing, accurately obtaining the surface haze distribution and value of a material is of the utmost importance in controlling and improving the surface quality of a material.

Currently, the techniques of surface inspection are mainly based on laser scattering; And methods or setups based on these technologies can detect imperceptible surface properties. When testing this property, a laser is irradiated onto the surface of the material to be inspected at an angle, and at the same time the sample to be inspected or the detector is rotated at high speed; A detector collects light scattered in all directions; Finally, the collected light signal is analyzed to obtain surface property information of the material. This method is very effective in detecting particles or materials on the surface of a material having a relatively high roughness, but conventional detection of surface haze signals is often hindered by various factors such as surface absorption, which affects the accuracy of surface haze test results. Therefore, micro-roughness such as surface haze cannot be effectively and accurately detected. It has always been difficult to accurately acquire surface haze signals to achieve accurate surface inspection.

As noted above, problems may arise when existing surface inspection methods or setups are used to detect surface haze. Conventional surface inspection methods or setups are primarily designed for the detection of higher roughness (eg, particles) on the surface of a material (such as a wafer). In the case of micro-roughness, such as surface haze expressed in values on the order of 10 ⁻⁶ (ppm), the signal is difficult to distinguish from noise signals by conventional instruments. Therefore, even if a surface haze signal is captured, a detection result that does not exclude a noise signal may be a "false" surface haze. These inspection results have few reference values for quality control of the wafer surface.

The present inventors have found that inspection of the surface haze of materials, particularly compound semiconductor wafers, using conventional surface inspection instruments may not be of valid reference significance -- because conventional methods do not test semiconductors under laser irradiation. This is because surface interference caused by photoluminescence of the material is not considered.

The present inventors also found that, as materials progress, photoluminescence of materials will be one of the non-negligible factors affecting accurate detection when performing surface haze inspection on a material surface using existing inspection setups. discovered that it can.

Photoluminescence refers to a phenomenon in which materials are excited under irradiation of an external light source to absorb energy and emit light. Photoluminescence in semiconductors works in this way: the material's valence band is filled with electrons - even in the case of impurity-free semiconductor materials; Due to thermal or photoexcitation, electrons in the upper part of the valence band are excited into the conduction band, thereby resulting in intrinsic conduction; Subsequently, electrons in the conduction band spontaneously transition from the conduction band to the valence band after lattice relaxation, and simultaneously emit photons having a specific wavelength. This is the process by which photoluminescence of the semiconductor material occurs. For ceramics or glass (e.g. luminescent glass, such as glass doped with a luminescent material), after the absorption of photons, there is also a similar photoluminescent process.

As is well known in the art, the light emission wavelength of a material is determined by the bandgap size of the material itself, and the specific relationship is represented by Formula I below:

_λem = 1240 / Eg (I)

here,

λ _em is the photoluminescence wavelength expressed in nm;

Eg is the bandgap size of the material expressed in eV.

In the above formula, the band gap (Eg) depends on the material as shown in FIG. In practice, once the material to be measured is determined, the emission wavelength can be calculated by this formula.

As representatives of elemental semiconductor materials, it has been found that indirect bandgap semiconductor materials such as silicon (Si) (band gap of 1.12 eV) and germanium (Ge) (band gap of 0.67 eV) are not considered because they cannot produce photoluminescence. .

However, the present inventors have developed compound semiconductor materials, especially III-V compound semiconductors such as gallium arsenide (GaAs) (with a band gap of 1.42 eV) and indium phosphide (InP) (with a band gap of 1.35 eV). It has been found that for direct bandgap semiconductor materials including, under normal detection conditions, the effects of photoluminescence of such materials on surface haze inspection cannot be neglected. It can be seen that the wave vectors of the initial and final states of the direct bandgap semiconductor do not change in the optical transition process and have high photoluminescence efficiency, and the photoluminescence wavelength is exactly the same as that of conventional Si-detectors ( or silicon photodetector), the luminous effect will significantly affect the surface haze inspection. Similarly, in the case of ceramics and glass (e.g., luminescent glass, such as glass doped with a luminescent material), the aforementioned problems may also occur.

Compound semiconductors are widely used in many fields, such as analog or digital mobile phones, pagers, base stations, wireless local area networks (LANs), satellite communications and microwave communications. The application value of these products continues to increase with the advent of communication technologies such as 5G. And quality control plays an even more important role in wafers made from such materials.

However, an effective method for accurately detecting the surface haze of a material (eg, a wafer, particularly a compound semiconductor wafer) in the field is desperately needed.

CN111272773A discloses a high-resolution system for detecting surface defects on semiconductor wafers, and a shifted illumination based defect inspection method and setup associated therewith. However, the purpose is not to detect surface haze, but to detect surface particles of semiconductors.

CN105870033A discloses a method of detecting surface scratches of polished semiconductor wafers, wherein the surface of the semiconductor wafer is irradiated with a pulsed laser and an energy damage threshold is defined to achieve rapid detection of scratches on the wafer surface. This method relates to scratches, and since the signal intensity of a scratch is of the same order as that of a particle, the signal can be easily captured. However, the surface haze test is silent.

CN112461861A discloses a method for evaluating the surface quality of a polished monocrystalline silicon wafer, and the surface haze test is characterized by the ratio of light intensity between scattered light and laser emission, commonly used in the art. Nevertheless, it mainly relates to a polished single crystal silicon wafer without considering that the optical signal of the scattered light detected by the detector does not completely originate from the surface haze (i.e., the detected optical signal may still contain an interference signal). . Therefore, the method disclosed in the present invention still has disadvantages for accurate surface haze inspection, especially for compound semiconductor wafers or direct bandgap semiconductor wafers.

According to the above analysis, a problem may arise when accurately detecting the surface haze distribution and / or value of a material (semiconductor substrate, especially compound semiconductor substrate or direct bandgap semiconductor substrate, etc.) using conventional general inspection methods, Accordingly, the surface haze distribution and/or value of the material cannot be accurately detected.

Although the criterion for evaluating whether a material is qualified in terms of the surface haze property differs for different uses of the material in the relevant field, the present inventors believe that the surface haze distribution and value detected due to interference signals may be higher than the actual material surface condition. , or if the actual surface haze condition (especially in the case of low surface haze) is obscured by the interfering signal and cannot be detected --- in this case, it was found that the result of the surface haze test is actually "false". Or even the tested material may be considered unacceptable because of such false results. Accordingly, such inspection results will not be of any criterion importance for quality control of the material. Moreover, such examination results will not be of any beneficial significance in tracing back or tracing the origins of the above problems.

Accordingly, there is a need to improve methods and setups for detecting material surface haze (including its distribution and/or values) to obtain accurate surface haze distributions and/or values.

SUMMARY OF THE INVENTION The present invention overcomes one or more of the above disadvantages of the prior art and provides an improved method and setup for surface haze detection of materials.

One aspect of the present invention provides a method for detecting surface haze of a material comprising:

- optionally, a preliminary inspection performed on the materials to identify that the materials are free of visible surface defects; and

- surface haze inspection to detect the surface haze of the material;

Here, the optical filter module is configured in the surface haze inspection setup to filter the photoluminescence signal of materials in the optical path to the detector, to avoid the photoluminescence signal being detected by the detector.

660 nm, 더 바람직하게는

490 nm의 파장을 갖는 1 파장 레이저(one-wavelength laser)일 수 있다.In some embodiments, surface haze inspection includes irradiating the material with incident light, wherein the incident light is a laser of any wavelength, preferably

660 nm, more preferably

It may be a one-wavelength laser having a wavelength of 490 nm.

In some embodiments, the filtering allows signal inspection to detect light having a wavelength less than the photoluminescence wavelength, preferably light having a wavelength no greater than the photoluminescence wavelength minus (−) 20 nm.

In some embodiments, the filtering is such that light having a wavelength in the range of the incident light wavelength ± 20 nm, preferably a wavelength in the range of the incident light wavelength ± 10 nm, more preferably the same wavelength as the incident light wavelength, can be detected in the signal detection step. do.

In some embodiments, the material is any material with a smooth surface; Preferably, the material is a semiconductor material, glass or ceramic; More preferably, the material is a semiconductor wafer; Even more preferably, the semiconductor wafer has a bandgap of 1.12 to 1.53 eV, preferably 1.35 to 1.43 eV.

In some embodiments, the semiconductor wafer is selected from compound semiconductor wafers, preferably direct bandgap semiconductor wafers, more preferably InP wafers or GaAs wafers.

Another aspect of the present invention provides a set-up for detecting the surface haze of a material, the set-up comprising:

a material-loading unit including a sample holder for holding the material;

660 nm, 더 바람직하게는

490 nm의 파장을 갖는 1 파장 레이저일 수 있고;a laser scanning unit including a laser source for emitting incident light; Preferably, the incident light is a laser of any wavelength, preferably

660 nm, more preferably

It may be a one-wavelength laser with a wavelength of 490 nm;

detector; a detector that responds to an optical signal preferably having a wavelength of 280 to 1100 nm; a signal inspection unit comprising a detector, which is preferably a visible light detector, more preferably a Si-detector or an integral detector; and

a data analysis unit including software for analyzing the signal detected by the signal inspection unit;

The setup for detecting the surface haze of the material further comprises an optical filter module comprising filters, filter coatings or combinations thereof, preferably low pass filters, band pass filters. , low pass filter coatings, band pass filter coatings, or combinations thereof; Preferably the optical filter module comprises band pass filters, a band pass filter coating or a combination thereof; Preferably, the optical filter module may be a separate module, or one or more filter coatings on the surface of the optical detector; the optical filter module is used to filter the photoluminescence signal of the material; The optical filter module is arranged in front of the detector in a propagation direction of an optical signal to be detected.

In some embodiments, the optical filter module includes an optical member capable of selectively transmitting light having a wavelength less than the photoluminescence wavelength, preferably not greater than (photoluminescence wavelength minus 20 nm).

In some embodiments, the optical filter module selectively emits light having a wavelength in the range of the incident light wavelength ± 20 nm, preferably a wavelength in the range of the incident light wavelength ± 10 nm, more preferably the same wavelength as the incident light wavelength. It includes an optical member capable of transmitting.

In some embodiments, the optical filter module is from the group consisting of filters, filter coatings and combinations thereof, preferably from the group consisting of low pass filters, band pass filters, low pass filter coatings, band pass filter coatings and combinations thereof. selected; Preferably, the optical filter module is selected from the group consisting of band pass filters, band pass filter coatings and combinations thereof; Preferably, the optical filter module can be a separate module, or a filter coating on the surface of the optical detector, or a combination thereof.

In some embodiments, the optical filter module has a signal light transmittance greater than 50%, preferably ≧95%, and more preferably ≧99%.

In some embodiments, the setup for detecting the surface haze of materials is used to detect any material with a smooth surface; Preferably, the material is a semiconductor material, glass or ceramic; More preferably, the material is a semiconductor wafer; More preferably, the semiconductor wafer is a wafer made of a semiconductor material having a bandgap of 1.12-1.53 eV, preferably 1.35 to 1.43 eV, preferably a wafer made of monoatomic semiconductors or compound semiconductors, and preferably Preferably a wafer made of a direct bandgap semiconductor material, and more preferably a wafer made of InP or GaAs.

The method and set-up of the present invention achieves a surface haze test that is reliable and accurate in terms of distribution and/or value by eliminating or reducing the interference caused by the photoluminescence of the material on the surface haze test.

1 is a schematic diagram of the energy band of a crystalline material.
2 is a schematic diagram of a method according to the present invention.
Figure 3 is a schematic diagram of a setup for detecting the surface haze of a material according to the present invention, each number designating one of the following elements: 1: laser source, 2: electrostatic chuck, 3: (placed on the electrostatic chuck ) material to be inspected, 4: optical filter module, 5: detector, 6: incident signal light, 7: signal light to be detected, 8: data analysis unit.
FIG. 4 shows surface haze test results performed on an N-type sulfur-doped (InP) wafer using an optical filter module according to the present invention, as illustrated in Example 1. Referring to FIG.
FIG. 5 shows surface haze test results performed on an N-type sulfur-doped (InP) wafer without using an optical filter module, as illustrated in Example 1. FIG.
6 shows surface haze test results performed on an N-type InP (Sulfur-doped) wafer using the optical filter module of the present invention, as illustrated in Example 2.
7 shows surface haze test results performed on an N-type sulfur-doped (InP) wafer without using an optical filter module, as illustrated in Example 2.
8 shows surface haze test results performed on an Un-type InP (undoped) wafer using the optical filter module of the present invention, as illustrated in Example 3.

FIG. 9 shows surface haze test results performed on an Un-type InP (non-doped) wafer without using an optical filter module as illustrated in Example 3. FIG.
FIG. 10 shows surface haze test results performed on an N-type GaAs (silicon doped) wafer using the optical filter module of the present invention, as illustrated in Example 4. FIG.
FIG. 11 shows surface haze test results performed on an N-type silicon-doped (GaAs) wafer without using an optical filter module, as illustrated in Example 4.
FIG. 12 shows surface haze test results performed on an N-type InP (sulfur doped) wafer using the optical filter module of the present invention, as illustrated in Example 5. FIG.
FIG. 13 shows surface haze test results performed on an N-type InP (sulfur doped) wafer without using an optical filter module, as illustrated in Example 5. FIG.
FIG. 14 shows surface haze test results performed on N-type InP (sulfur-doped) wafers using the optical filter module of the present invention, as illustrated in Example 6. FIG.
FIG. 15 shows surface haze test results performed on an N-type InP (sulfur doped) wafer without using an optical filter module, as illustrated in Example 6. FIG.
16 shows surface haze test results performed on an N-type InP (sulfur doped) wafer using the optical filter module of the present invention, as illustrated in Example 7.
FIG. 17 shows surface haze test results performed on an N-type InP (sulfur-doped) wafer without using an optical filter module, as illustrated in Example 7.

FIG. 18 shows surface haze test results performed on N-type InP (sulfur-doped) wafers using the optical filter module of the present invention, as illustrated in Example 8. FIG.
FIG. 19 shows surface haze test results performed on an N-type InP (sulfur doped) wafer without using an optical filter module, as illustrated in Example 8.

Hereinafter, embodiments of the present invention will be described in detail. The following examples are illustrative only and should not be construed as limiting the invention. The protection scope of the present invention is defined only by the claims. Further, in the practice of the present invention, not all features described in the following embodiments must be included. Additionally, in the context of the present invention, there are many combinations of these features, and general and preferred definitions may be combined with each other. New technical solutions formed by this combination are also covered by the present invention.

As shown in Figure 2, one aspect of the present invention provides a method for detecting the surface haze of a material, the method comprising:

- optional preliminary inspection performed on the material to identify that the material is free of visible surface defects for subsequent surface haze inspection; and

- Including; surface haze inspection to detect the surface haze of the material,

Here, the optical filter module is configured in the surface haze inspection setup to filter the photoluminescence signal of the material in the light path to the detector, to avoid the photoluminescence signal being detected.

In some embodiments, surface haze inspection is performed through a surface haze inspection setup. The surface haze inspection setup is equipped with an optical filter module that can filter the photoluminescence signal of the material, but does not affect the detection of the desired signal.

As used herein, the term "surface haze" (or "haze") refers to the surface morphology (i.e., micro-roughness) and non-directional properties caused by imperfections on or near the surface of a high concentration. (non-directional) light scattering phenomenon. Generally, "surface haze" is used to describe the non-uniformity of a surface on a scale below the detection limit of surface particle size. Therefore, only samples that pass surface granularity detection (in preliminary inspection) will undergo surface haze scanning and detection. Haze values and distributions reflect the degree of micro-roughness of the material surface.

In some embodiments, the material is a semiconductor material, glass, or ceramic. In some embodiments, the material is preferably a semiconductor wafer, particularly a cleaned and dried semiconductor wafer. In some embodiments, the glass is luminescent, preferably a glass to which a luminescent material has been added.

As used herein, the term “wafer” refers to a substrate (with or without an epitaxial layer) formed of semiconductor or non-semiconductor materials. Examples of wafers include, but are not limited to, monocrystalline silicon, monocrystalline germanium, gallium arsenide, or indium phosphide. In some embodiments, the wafer is a substrate (ie, a bare wafer). In some embodiments, a wafer may also include one or more layers of different materials formed on a substrate.

In some embodiments, the semiconductor wafer is a semiconductor substrate. In other embodiments, the semiconductor wafer may also be an epitaxial wafer.

As used herein, the term "substrate" refers to a clean single crystal wafer having a specific lattice plane and suitable electrical, optical and mechanical properties, which is used to grow an epitaxial layer thereon.

In some embodiments, the semiconductor wafer has photoluminescent properties.

As used herein, the term “preliminary inspection” refers to granular inspection/check of the wafer surface. The preliminary inspection may be performed by various methods or setups generally known in the art. In some embodiments, the preliminary examination is a light assisted examination.

As used herein, the term "light-assisted inspection" refers to visually checking the wafer surface under high intensity light.

In some embodiments, the luminance of the light source used for preliminary inspection falls within a typical range of luminance used for conventional inspection. Preferably, the luminance is 300,000 lux or more. More preferably, the luminance is 400,000 lux or more.

As used herein, the term "luminance" means the luminous flux of visible light received per unit area, i.e., luminous intensity (lux, lx), which is used to indicate the intensity and/or degree of light with which the surface of an object is irradiated. is the physical quantity used.

For semiconductor wafers, it is known in the art that excessive roughness of the wafer surface will affect the detection of small local light-scatter (including surface haze). Preliminary inspection is arranged to select semiconductor wafers free of major defects (eg, visible defects) from the finished product (ie, wafers that have been subjected to polishing, cleaning, drying, etc.) for further surface haze detection, thereby ensuring wafer quality. further improve In this application, a preliminary inspection is conducted to select or identify materials free from visible surface defects, and such materials are further detected for surface haze. That is, wafers with visible surface defects are directly considered unqualified, and no further surface haze detection will be performed.

As used herein, the term “visible defect” refers to defects on the wafer surface that are visible under high intensity light, such as scratches, chemical residues, peel-like defects, bright spots fields, particles, twin lamellae, edge breakage, cracks, shallow pits, knife marks, streaks, corrosion pits, stains, Refers to poorly polished areas and micro-protrusions. Thus, a material having no visible surface defects (ie, a semiconductor wafer) means that none of the above-mentioned defects are found on its surface.

As used herein, the term "cleaning" refers to removing unwanted residues from the surface of materials (eg, wafers).

In some embodiments, preliminary testing is optional. In some embodiments, no pre-test is performed. In some embodiments, for some materials, such as ceramic or glass, the preliminary inspection step may be omitted.

In some embodiments, according to the method of the present invention, when the material to be inspected is a semiconductor wafer, additional steps such as cleaning or drying the wafer prior to preliminary inspection are also included. These steps may be performed using conventional methods and apparatus in the art.

In some embodiments, the setup used for surface haze inspection may be a surface detection setup commonly used in the art. Preferably, surface haze inspection can be performed using wafer surface detection systems commonly used in the art, such as but not limited to KLA Surfscan, KLA Candela series or Unity Lightspeed inspection systems.

660 nm, 바람직하게는

490 nm의 파장을 갖는 레이저이다. 일부 실시예들에서, 입사 광은 < 490 nm 미만의 파장을 갖는다. 바람직하게는 파장

490 nm를 갖는 블루-바이올렛 레이저를 입사 광으로서 사용하여, 표면 검사의 검출성을 향상시키는 것이 가능한 것으로 밝혀졌다. 더욱 바람직하게는, 입사 광은 405 nm, 473 nm 또는 488 nm의 파장을 갖는 레이저이고; 특히 바람직하게는, 입사 광은 473 nm의 파장을 갖는 레이저이다. 일부 실시예에서, 655 nm의 파장을 갖는 레이저가 또한 입사 광으로서 사용될 수 있다.In some embodiments, surface haze inspection involves irradiating the wafer to be detected with incident light, which can be a laser having a wavelength commonly used in the art for wafer surface detection. In some embodiments, the incident light is a short-wavelength laser. In some embodiments, the incident light may be a one wavelength laser with any wavelength falling within the red or blue-violet bands of the spectrum. In some embodiments, the incident light is

660 nm, preferably

It is a laser with a wavelength of 490 nm. In some embodiments, the incident light has a wavelength <490 nm. preferably the wavelength

It has been found that it is possible to improve the detectability of surface inspection by using a blue-violet laser with 490 nm as the incident light. More preferably, the incident light is a laser with a wavelength of 405 nm, 473 nm or 488 nm; Particularly preferably, the incident light is a laser with a wavelength of 473 nm. In some embodiments, a laser with a wavelength of 655 nm may also be used as the incident light.

In some embodiments, surface haze inspection includes signal detection. Preferably, signal detection is detecting an optical signal of any wavelength, which may be 1100 nm or less, preferably 280 to 1100 nm, more preferably 280 to 980 nm, particularly preferably 350 to 850 nm. Preferably, the signal detection is for detecting an optical signal having the same wavelength as that of the incident light.

As used herein, the term "photoluminescence" refers to a phenomenon in which a material is excited and absorbs energy to emit light when exposed to an external light source. Taking a semiconductor material as an example, in photoluminescence, electrons are excited by light, transition from the valence band to the conduction band, then return to the valence band through lattice relaxation, and at the same time generate photons. refers to the process of releasing

As used herein, the term “photoluminescence signal” means an optical signal generated by photoluminescence of a material.

For a material to be detected having an energy band structure, the photoluminescence wavelength of the material can be determined using the formula (I) above in order to select a suitable optical filter module. For crystalline materials such as ceramic and semiconductor materials, Eg is the bandgap width of the material itself; In the case of an amorphous material such as glass, especially glass with a light emitting material, Eg is the width of the bandgap of the light emitting material.

As used herein, the term "bandgap width" refers to the energy difference between the lowest energy level of the conduction band and the highest energy level of the valence band of a material.

The inventors have found that when the inspection of the surface state is performed, the photoluminescence of the tested material influences the accurate detection of the surface haze. This is especially true when the tested material has a low surface haze signal. Therefore, in order to accurately detect the surface haze, it is necessary to remove and reduce the interference by filtering the photoluminescence signal of the material.

As used herein, the term “filtering” refers to substantially eliminating interference or effects on surface haze detection by substantially removing undesirable optical signals (such as optical signals generated by photoluminescence of the material being tested). refers to the removal or reduction of

In order to effectively remove the non-surface-haze signal (which, according to the present invention, generally refers to the photoluminescence signal of the material), in some embodiments, the photoluminescence signal of the wafer is inspected for surface haze. filtered during

In some embodiments, in surface haze inspection, filtering enables only light having a wavelength less than the photoluminescent wavelength, preferably no greater than the photoluminescent wavelength minus 20 nm, to be detected in the signal inspection step. Preferably, only light having a wavelength equal to that of the incident light is detected in the signal inspection step.

Alternatively, in some embodiments, in surface haze checks, filtering is performed in the range of plus or minus (±) 20 nm of the wavelength of the incident light, preferably in the range of plus or minus 10 nm of the wavelength of the incident light, and more preferably in the range of Only light having the same wavelength as that of incident light enables detection in the signal detecting step.

In some embodiments, in surface haze inspection, filtering includes selecting an optical filter module. For example, in the case of surface haze inspection of a semiconductor wafer, the selection of an optical filter module can be made by a) calculating the photoemission wavelength λ _em of the semiconductor using formula (I) above; b) selecting an optical filter module that transmits light having a wavelength less than λ _em .

Preferably, the optical filter module includes filters and/or filter coatings. In some embodiments, the filtering step includes selecting a low pass filter or filter coating having a cut-off wavelength above the incident light wavelength (λ _ex ) and below the photoemission wavelength (λ _em ). . Preferably, the cut-off wavelength is greater than (λ _ex + 20) nm and less than (λ _em -20) nm. In some embodiments, the step of filtering is a band that transmits light having a wavelength of (λ _ex ± 20) nm, preferably a wavelength of (λ _ex ± 10) nm, more preferably the same wavelength as the wavelength of the incident light. and selecting a pass-through filter or filter coating.

In some embodiments, according to the method of the present invention, the tested material is any material with smooth surfaces. Preferably, the material is selected from semiconductor materials, glass or ceramics; More preferably, the material is a semiconductor wafer. In some embodiments, the glass is a luminescent glass, and preferably a glass doped with a luminescent material. Preferably, the semiconductor wafer has a band gap of 1.12-1.53 eV, preferably 1.35-1.43 eV. In some embodiments, the material of the semiconductor wafer is selected from elemental semiconductor materials or compound semiconductor materials, and preferably compound semiconductor materials. In some embodiments, the material of the semiconductor wafer is selected from direct bandgap semiconductor materials, preferably having a bandgap between 1.12 and 1.53 eV, or more preferably between 1.35 and 1.43 eV. Preferably, the material of the semiconductor wafer is InP or GaAs.

In some embodiments, according to the method of the present invention, the incident light source has a wavelength of 473 nm and the optical filter module has cut-off bands of <460 nm and > 485 nm and thus a transmission band of 460 to 485 nm. Particularly preferred is a band pass filter or filter coating, and the transmittance at a wavelength of 473 nm is 100%. These conditions can be used to detect the surface haze of wafers of III-V compound semiconductors, such as wafers of gallium arsenide (GaAs) or indium phosphide (InP).

In some embodiments, the surface haze inspection includes a material loading step and a data analysis step.

Another aspect of the present invention provides a setup for detecting the surface haze of a material, as shown in FIG. 3, comprising:

a material loading unit comprising a sample holder (e.g., electrostatic chuck 2) for holding the material 3;

a laser-scanning unit comprising a laser source 1 emitting incident light 6;

a signal detection unit comprising a detector 5; and

a data analysis unit 8 comprising test software for analyzing the signals detected by the signal examination unit;

The setup for detecting the surface haze of a material further comprises an optical filter module 4 for filtering the photoluminescence signal of the material 3; The optical filter module 4 is arranged in front of the detector 5 in the propagation direction of the optical signal 7 to be detected.

As used herein, the term “sample holder” refers to a setup that holds and holds a sample to be detected during a detection process. In some embodiments, sample holders are those commonly used for surface detection in the art. Preferably, the sample holder is an electrostatic chuck. When the material to be detected is a wafer, the sample holder is a wafer chuck.

In some embodiments, the material loading unit further comprises material clamping means (including but not limited to a manipulator and back-contact or edge-contact clamping means) for automatically loading the material to be detected on the sample holder. .

In some embodiments, optionally, the setup for detecting the surface haze of a material of the present invention includes a pre-inspection unit. In some embodiments, the preliminary inspection unit is a setup commonly used for preliminary inspection of materials in the art (eg, semiconductor wafers). In some embodiments, the pre-inspection unit is a useful setup for light-assisted inspection. In some embodiments, the preliminary inspection setup is a light source, preferably a high-intensity light source. Preferably, the high-intensity light source may be high-brightness halogen light, but is not limited thereto. In some embodiments, the preliminary inspection unit includes a light source having a luminance of 300,000 lx or more, preferably 400,000 lx or more.

In some embodiments, in the laser scanning unit, a laser source for emitting incident light may emit a laser having a determined wavelength. In some embodiments, the laser source preferably emits a laser with a wavelength within the red or blue-violet bands of the spectrum, preferably with a wavelength within the blue-violet band of the spectrum. In some embodiments, the laser source emits a laser with a wavelength of ≤660 nm, preferably ≤490 nm. It has been found possible to improve the detectability of surface inspection by using a laser source with a wavelength in the blue-violet band of the spectrum, in particular <490 nm. Preferably, the laser source can emit a laser with a wavelength of 405 nm, 473 nm or 488 nm. In some embodiments, the laser source may emit a laser with a wavelength of 655 nm. In some embodiments, the laser source may preferably emit a laser having a wavelength of 473 nm.

In some embodiments, the signal detection unit is a device commonly used in the art, including but not limited to receivers and detectors. Preferably, the signal detection unit is a detector, more preferably the signal detection unit is an integrated detector. In some embodiments, detectors may be those commonly used in the art for wafer surface detection. A detector is used to collect and detect the resulting scattered light signal by illuminating the surface of the semiconductor to be detected with incident light. More preferably, the detector responds to an optical signal having a wavelength of 1100 nm or less, preferably 280 to 1100 nm, more preferably 280 to 980 nm, even more preferably 350 to 850 nm. More preferably, the detector is a visible-light responding detector, even more preferably a Si-detector.

In embodiments of the present invention, the data analysis unit includes test software for analyzing the signal detected in the signal detection unit, and the test software is commercial software known in the art. In some embodiments the test software is integrated into a commercial surface detection device.

The inventors of the present invention, in order to accurately inspect the surface haze, the photoluminescence signal of the material (semiconductor substrate, etc.) to be detected must be removed to the extent that it cannot be detected by the detector, or it is too weak to affect the detection of the surface haze signal by the detector. However, it has been found that the optical signal generated by the surface haze can be accurately captured by the detector to provide an accurate result of the surface haze distribution and value. Using the optical filter module according to the present invention can effectively filter/remove/reduce undesirable disturbing signals (i.e., specific surface haze signals, e.g., preferably photoluminescence signals), thus semiconductor for inspection. The surface haze signal can be accurately collected and detected by the detector while minimizing or eliminating the influence of the material's photoluminescence signal (particularly in the case of low surface haze). Conversely, without the optical filter module of the present invention (eg, when conventional surface inspection equipment is used), the surface haze signal is interfered with or even masked by the photoluminescent signal, and the material (eg, It is readily understood that the actual value and/or distribution of the surface haze of a semiconductor wafer) will not (or even possibly cannot be obtained) be accurately obtained.

According to the present invention, an optical filter module is used to "intercept" light of an undesired wavelength while transmitting light whose wavelength falls within a desired range.

In some embodiments, the optical filter module includes one or more optical members that selectively transmit light of a specific wavelength.

In some embodiments, the optical filter module includes an optical member that selectively transmits light having a wavelength smaller than the photoluminescent wavelength (λ _em ). Preferably, the optical filter module includes an optical member that selectively transmits light having a wavelength of (λ _em - 20) nm or less.

In some embodiments, the optical filter module includes an optical member that selectively transmits light having a wavelength range of (λ _ex ± 20) nm. Preferably, the optical filter module includes an optical member that selectively transmits light having a wavelength range of (λ _ex ± 10) nm. More preferably, the optical filter module includes an optical member that selectively transmits light having a wavelength equal to λ _ex .

According to the invention, preferably the optical filter module is selected from filters, filter coatings or combinations thereof, preferably from low pass filters, band pass filters, low pass filter coatings, band pass filter coatings or combinations thereof. In some embodiments, the preferably optical filter module includes a low pass filter, a low pass filter coating, or a combination thereof. In some embodiments, the preferably optical filter module includes a band pass filter, a band pass filter coating, or a combination thereof.

As used herein, the terms "filter" and "filter coating" both refer to an optical filter module used to selectively transmit light having a wavelength in a specific irradiation wavelength band.

As used herein, the term “low-pass filter/coating” refers to an optical filter module capable of transmitting light with wavelengths below a certain value and blocking light with wavelengths above the value. .

As used herein, the term “band-pass filter/film” refers to an optical filter module capable of transmitting light with wavelengths within a specific range and blocking light with wavelengths outside the range. .

In some embodiments, filters or filter coatings can be of any type known in the art. Preferably, an optical filter is constructed in front of the detector in a direction of propagation of an optical signal to be detected, in a manner commonly known in the art. In some embodiments, a filter is configured between the material loading unit and the signal detection unit. Preferably, the filter coating is arranged on the detector via methods known in the art on the detector. Preferably, the filter coating is plated on the surface of the detector.

In some embodiments, the cutoff wavelength of the selected low pass filter or filter coating is greater than the excitation light wavelength (λ _ex ) and less than the photoemission wavelength (λ _em ). Preferably, the cut-off wavelength of the selected low-pass filter or filter coating is greater than (λ _ex + 20) nm and less than (λ _em - 20) nm.

In some embodiments, the transmission wavelength of the selected band pass filter or filter film is (λ _ex ± 20) nm; Preferably, the transmission wavelength is (λ _ex ± 10) nm.

In some embodiments, an optical filter module of the present invention may include a filter or filter coating. In other embodiments, an optical filter module may include two or more filters of the same or different types. In other embodiments, an optical filter module may include two or more filter coatings of the same or different types. In another embodiment, an optical filter module of the present invention may include a combination of at least one filter and at least one filter coating, wherein the filters and filter coatings may be of the same or different types and may have different transmission wavelengths. can have

Interfering optical signals with undesirable wavelengths (including but not limited to photoluminescent signals) by using an optical filter module that includes one or more filters and/or filter coatings of the same or different types having various transmission wavelengths. can be filtered, and thus a more accurate surface haze detection result can be achieved.

Optical filters/coatings selected for different semiconductor materials may be those shown in Table 1 (but not limited thereto).

Table 1: Cut-off wavelength ranges of low-pass filters/coatings and transmission wavelength ranges of band-pass filters/films that can be selected for different semiconductor materials.

In some embodiments, the optical filter module may have a transmittance of ≧50%, preferably a transmittance of ≧95%, more preferably a transmittance of ≧99%.

In some embodiments, the optical filter module of the present invention includes a filter suitable according to the material of the semiconductor wafer (semiconductor substrate, etc.) to be detected, in order to automatically and selectively acquire the surface haze distribution and value of wafers made of different semiconductor materials. can be selected automatically. In some embodiments, the optical filter module of the present invention may include a filter selection unit: after being given the information of the semiconductor material type of the wafer to be tested, the computer selects an appropriate optical filter module (e.g. filter or filter coating). ), and then automatically change the appropriate optical components to be ready for detection.

In some embodiments, setups for inspecting the surface haze of materials according to the present invention are useful for inspecting wafers of semiconductor materials having a band gap of 1.12 to 1.53 eV, more preferably 1.35 to 1.42 eV. In some embodiments, the inspection setup of the present invention is used to detect the surface haze of wafers made of elemental semiconductor materials or compound semiconductor materials, preferably wafers made of compound semiconductor materials. In some embodiments, an inspection setup of the present invention is a wafer made of direct bandgap semiconductor material, preferably with a bandgap of 1.12 to 1.53 eV, more preferably 1.35 to 1.42 eV. It is used to inspect the surface haze of wafers. In some embodiments, the inspection setup of the present invention is used to inspect wafers of InP or GaAs.

example

Example 1

A 3-inch N-type InP (sulfur-doped) wafer was subjected to surface haze inspection. After being cleaned and dried, the wafer was further processed in the following steps:

1. Preliminary inspection

The cleaned wafers were inspected with the aid of a high intensity light source (purchased from Yamada Optics, Japan). The luminance was 400,000 lx or more. During inspection, slowly move the wafer clockwise to determine if there are any visible defects (eg, scratches, chemical residues, and peel-like defects) on the wafer surface. It was rotated and observed carefully under a high-intensity light source in a counterclockwise direction. Wafers that are free of visible defects, i.e., pass the preliminary inspection, will be inspected for surface haze.

2. Surface Haze Inspection

A LIGHTSpEED inspection system under the 4See series of UnitySC company (France) was used.

a. Wafers that passed preliminary inspection were placed on a wafer holder (ie, wafer electrostatic chuck) of the inspection system. As the incident light, a blue laser with a wavelength of 473 nm was used.

b. The optical filter module was selected in the following way: the wafer to be inspected was made of an InP material with a bandgap of 1.35 eV, so the photoluminescence wavelength of the material was calculated to be λ _em = 1240 / 1.35 = 918 nm. Therefore, an optical filter module capable of filtering an optical signal of a wavelength of 918 nm --- a low-pass filter having a cut-off wavelength of less than 918 nm can be selected. Specifically, in this embodiment, a low-pass filter having a cut-off wavelength of 550 nm and a pass band transmittance of 95% was used.

c. Signal Inspection and Analysis

A suitable optical filter module was selected and configured in front of the signal inspection unit (i.e. Si-detector) in the direction of propagation of the optical signal to be detected. Then, the wafer was scanned with the laser scanning unit, the scattered light signal passing through the optical filter module was inspected by the Si-detector, and the detected signal data was analyzed by the data analysis unit (including built-in test software). The results of the surface haze test are shown in FIG. 4 .

When the optical filter module was not used, the same wafer that passed the preliminary inspection was subjected to the surface haze inspection under the same conditions. The result is shown in FIG. 5 .

5 shows the surface haze of an N-type InP wafer detected without using an optical filter module. As shown in Fig. 5, the surface haze distribution on the wafer surface was observed blurry; High surface haze intensities were observed in regions a, b, c and d, with intensity values of 2.223 ppm, 2.134 ppm, 1.324 ppm and 1.153 ppm, respectively; Thus, the median value for the surface haze of the entire wafer was 1.877 ppm. In general, when the median surface haze intensity of an InP wafer is no greater than 0.15 ppm, the surface haze of the wafer will be considered acceptable. Therefore, based on the above results, the wafer will be considered unacceptable.

4 is a diagram showing the surface haze of the same N-type InP wafer detected using the optical filter module of the present invention. As shown in FIG. 4, high surface haze intensities were observed in the a, b, c, and d regions of the wafer, but the intensity values were 0.253 ppm, 0.142 ppm, 0.041 ppm, and 0.023 ppm, respectively. In addition, the surface haze distribution on the wafer surface was very clear, especially in the region d where the boundary line of the surface haze could be clearly observed. The median surface haze of all wafers was 0.036 ppm. Thus, the wafer was indeed a wafer with an acceptable surface haze.

Comparing FIG. 4 and FIG. 5, as shown in FIG. 5, the surface haze values detected in each area of the wafer indicated by a, b, c, and d are actually false results due to photoluminescence of the wafer material, and It can be seen that due to interference by photoluminescence, an indefinite distribution of surface haze distribution can be observed. On the other hand, as shown in FIG. 4, after using the optical filter module of the present invention, a more accurate surface haze distribution map (FIG. 4) and a more accurate surface haze value can be obtained by effectively removing the emission signal of the wafer. , was able to enable reliable quality evaluation of the wafer.

Similar results can be obtained when the optical filter module used herein is optionally a band pass filter (or else a filter coating, or a combination thereof) with a center wavelength of 473 nm.

example 2

A 3-inch N-type InP (sulfur-doped) wafer was subjected to surface haze inspection. After being cleaned and dried, the wafer was further processed in the following steps:

1. Preliminary inspection

The cleaned wafers were inspected with the aid of a high intensity light source (purchased from Yamada Optics, Japan). The luminance was 400,000 lx or more. The process and criteria for light-assisted inspection were identical to those described in Example 1. Wafers that passed preliminary inspection were used for surface haze inspection.

2. Surface Haze Inspection

A LIGHTSpEED inspection system under the 4See series of UnitySC company (France) was used.

a. Wafers that passed preliminary inspection were placed on a wafer holder (ie, wafer electrostatic chuck) of the inspection system. A blue laser with a wavelength of 473 nm was used as the incident light.

b. The optical filter module was selected in the following way: the wafer to be inspected was made of an InP material with a bandgap of 1.35 eV, so the photoluminescence wavelength of the material was calculated to be λ _em = 1240 / 1.35 = 918 nm. Therefore, an optical filter module capable of filtering an optical signal of a wavelength of 918 nm --- a low-pass filter having a cut-off wavelength of less than 918 nm can be selected. Specifically, in this embodiment, a low-pass filter having a cut-off wavelength of 550 nm and a pass band transmittance of 90% was used.

c. Signal Inspection and Analysis

A suitable optical filter module was selected and configured in front of the signal inspection unit (i.e. Si-detector) in the direction of propagation of the optical signal to be detected. Then, scanning the wafer with a laser scanning unit; The scattered light signal passing through the optical filter module was inspected by the Si-detector, and the detected signal data was analyzed by the data analysis unit (including built-in test software). The results obtained after the surface haze test are shown in FIG. 6 .

When the optical filter module was not used, the surface haze test was performed under the same conditions for the same wafer that passed the preliminary test. The result is shown in FIG. 7 .

7 shows the surface haze of an N-type InP wafer detected without using an optical filter module. As shown in FIG. 7, a high surface haze value of 3.562 ppm was observed in the central region of the wafer. Generally, the surface haze of an InP wafer will be considered acceptable when the median value of haze intensity on the surface of the wafer is no greater than 0.15 ppm. Therefore, based on the above inspection results, the wafer was considered to have unacceptable surface haze characteristics.

6 shows the surface haze of an N-type InP wafer detected using the optical filter module of the present invention. As shown in Figure 6, no high-intensity surface haze regions were observed, and the wafer exhibited a uniform surface; The surface haze value was 0.024 ppm. Thus, the wafers actually had acceptable surface haze properties.

Comparing Figures 6 and 7, it can be seen that the "high" intensity surface haze distribution in the central region of the wafer as shown in Figure 7 is actually a false result due to the photoluminescence of the wafer material. In contrast, after using the optical filter module of the present invention, it was possible to obtain a more accurate surface haze distribution map (FIG. 6) and a more accurate surface haze value by effectively removing the emission signal of the wafer.

Similar results can be obtained when the optical filter module used herein is optionally a band pass filter (or else a filter coating, or a combination thereof) with a center wavelength of 473 nm.

Example 3

A 3-inch N-type InP (undoped) wafer was subjected to surface haze inspection. After being cleaned and dried, the wafer was further processed in the following steps:

1. Preliminary inspection

The cleaned wafers were inspected with the help of a high intensity light source (purchased from Yamada Optics, Japan). The luminance was 400,000 lx or more. The process and criteria of light-assisted inspection were identical to those described in Example 1. Wafers that passed preliminary inspection were used for surface haze inspection.

2. Surface Haze Inspection

A LIGHTSpEED inspection system under the 4See series of UnitySC company (France) was used.

a. A wafer that passed preliminary inspection was placed on a wafer holder (ie, wafer electrostatic chuck) of the inspection system. A blue laser with a wavelength of 473 nm was used as the incident light.

b. The optical filter module was selected in the following way: The wafer to be inspected was made of an InP material with a bandgap of 1.35 eV, so the photoluminescence wavelength of the material was calculated to be: λ _em = 1240 / 1.35 = 918 nm . Therefore, an optical filter module capable of filtering an optical signal of a wavelength of 918 nm --- a low-pass filter having a cut-off wavelength of less than 918 nm can be selected. Specifically, in this embodiment, a low-pass filter having a cut-off wavelength of 550 nm and a pass band transmittance of 90% was used.

c. Signal Inspection and Analysis

A suitable optical filter module was selected and configured in front of the signal inspection unit (i.e. Si-detector) d in the direction of propagation of the optical signal to be detected. Then, the wafer was scanned with the laser scanning unit, the scattered light signal passing through the optical filter module was inspected by the Si-detector, and the detected signal data was analyzed by the data-analysis unit (with built-in test software). The results obtained after the surface haze test are shown in FIG. 8 .

When the optical filter module was not used, the same wafer that passed the preliminary inspection was subjected to the surface haze inspection under the same conditions. The result is shown in FIG. 9 .

9 shows the surface haze of an N-type InP wafer detected without using an optical filter module. As shown in FIG. 9, a high surface haze value of 4.026 ppm was observed in the central region of the wafer. Generally, the surface haze of an InP wafer will be considered acceptable when the median haze intensity on the surface of the wafer is no greater than 0.15 ppm. Therefore, based on the above inspection results, the wafer was considered to have unacceptable surface haze characteristics.

8 shows the surface haze of an N-type InP wafer detected using the optical filter module of the present invention. As shown in FIG. 8, no high-intensity surface haze region was observed, the surface of the wafer was uniform, and the surface haze value was 0.028 ppm. Thus, the wafers actually had acceptable surface haze properties.

Comparing FIG. 8 with FIG. 9 , it can be seen that the “high” intensity of the surface haze distribution in the central region of the wafer as shown in FIG. 9 is actually a false result caused by photoluminescence of the wafer material. In contrast, after using the optical filter module of the present invention, a more accurate surface haze distribution map (FIG. 8) and a more accurate surface haze value could be obtained by effectively removing the emission signal of the wafer.

Similar results can be obtained when the optical filter module used herein is optionally a band pass filter (or else a filter coating, or a combination thereof) with a center wavelength of 473 nm.

Example 4

A 4-inch N-type GaAs (silicon-doped) wafer was subjected to surface haze inspection. After being cleaned and dried, the wafer was further processed in the following steps:

1. Preliminary inspection

The cleaned wafers were inspected with the aid of a high intensity light source (purchased from Yamada Optics, Japan). The luminance was 400,000 lx or more. The process and criteria of light-assisted inspection were identical to those described in Example 1. Wafers that passed preliminary inspection were used for surface haze inspection.

2. Surface Haze Inspection

A LIGHTSpEED inspection system under the 4See series of UnitySC company (France) was used.

a. A wafer that passed preliminary inspection was placed on a wafer holder (ie, wafer electrostatic chuck) of the inspection system. A blue laser with a wavelength of 473 nm was used as the incident light.

b. The optical filter module was selected in the following way: the wafer to be inspected was made of GaAs material with a bandgap of 1.42 eV, so the photoluminescence wavelength of the material was calculated to be λ _em = 1240 / 1.42 = 873 nm. Accordingly, an optical filter module capable of filtering an optical signal of a wavelength of 873 nm - a low pass filter module having a cut-off wavelength of less than 873 nm - can be selected. Specifically, in this embodiment, a low-pass filter having a cut-off wavelength of 550 nm and a pass band transmittance of 90% was used.

c. Signal Inspection and Analysis

A suitable optical filter module was selected and configured before the signal inspection unit (i.e. Si-detector) in the direction of propagation of the optical signal to be detected. Then, the wafer was scanned with the laser scanning unit, the scattered light signal passing through the optical filter module was inspected by the Si-detector, and the detected signal data was analyzed by the data analysis unit (with built-in test software). The results obtained after the surface haze test are shown in FIG. 10 .

When the optical filter module was not used, the same wafer that passed the preliminary inspection was subjected to the surface haze inspection under the same conditions. The result is shown in FIG. 11 .

11 shows the surface haze of an N-type GaAs wafer detected without using an optical filter module. As shown in FIG. 11, several regions with high surface haze were scattered in a butterfly shape on the wafer, and the intensity value was 0.852 ppm. As is generally recognized in the art, a GaAs wafer is considered to have passed the surface haze test when it has a surface haze value of less than 0.250 ppm. Therefore, based on the above inspection results, the wafer was considered to have unacceptable surface haze characteristics.

10 shows the surface haze of an N-type GaAs wafer detected using the optical filter module of the present invention. As shown in FIG. 10, no high-intensity surface haze region was observed, the wafer surface was uniform, and the surface haze value was 0.176 ppm. Thus, the wafers actually had acceptable surface haze properties.

Comparing FIG. 10 with FIG. 11 , it can be seen that some areas with high intensity of surface haze scattered on the wafer are false results caused by the photoluminescence signal of the wafer material, as shown in FIG. 11 . In contrast, after using the optical filter module of the present invention, the photoluminescence signal of the wafer was effectively removed, and -- as evident from the comparison of FIGS. 10 and 11 , after using the optical filter module, a butterfly shape of high surface haze Scattering regions will not be observed, which makes it possible to obtain a more accurate surface haze distribution map and more accurate surface haze values.

Similar results can be obtained when the optical filter module used herein is optionally a band pass filter (or else a filter coating, or combination thereof) with a center wavelength of 473 nm.

Example 5

A surface haze test was performed on a 3-inch N-type InP (sulfur-doped) wafer. After being cleaned and dried, the wafer was further processed in the following steps:

1. Preliminary inspection

The cleaned wafers were inspected with the aid of a high intensity light source (Yamada Optics, Japan). The luminance was 400,000 lx or more. The process and criteria of light-assisted inspection were the same as described in Example 1. Wafers that passed preliminary inspection were used for surface haze inspection.

2. Surface Haze Inspection

A LIGHTSpEED inspection system under the 4See series of UnitySC company (France) was used.

a. A wafer that passed preliminary inspection was placed on a wafer holder (ie, wafer electrostatic chuck) of the inspection system. A blue laser with a wavelength of 473 nm was used as the incident light.

b. The optical filter module was selected in the following way: the wafer to be inspected was made of an InP material with a bandgap of 1.35 eV, so the photoluminescence wavelength of the material was calculated to be: λ _em = 1240 / 1.35 = 918 nm . Therefore, an optical filter module capable of filtering an optical signal having a wavelength of 918 nm --- a low-pass filter having a cut-off wavelength of less than 918 nm can be selected. Specifically, in this embodiment, a low-pass filter having a cut-off wavelength of 490-540 nm and a pass band transmittance of 90% was used.

c. Signal Inspection and Analysis

A suitable optical filter module was selected and configured before the signal inspection unit (i.e. Si-detector) in the direction of propagation of the optical signal to be detected. Then, the wafer was scanned with the laser scanning unit, the scattered light signal passing through the optical filter module was inspected by the Si-detector, and the detected signal data was analyzed by the data analysis unit (with built-in test software). The results obtained after the surface haze test are shown in FIG. 12 .

When the optical filter module was not used, the surface haze test was performed on the same wafer that passed the preliminary test under the same conditions. The result is shown in FIG. 13 .

13 shows the surface haze of an N-type InP wafer detected without using an optical filter module. As shown in FIG. 13, a high surface haze value of 1.791 ppm was observed in the central region of the wafer. As is generally accepted in the art, when an InP-based wafer has a surface haze intensity value of less than 0.150 ppm, it is considered to have passed the surface haze test. Therefore, based on the inspection results, the wafer was considered to have unacceptable surface haze characteristics.

12 shows the surface haze of an N-type InP wafer detected using the optical filter module of the present invention. As shown in FIG. 6, no high-intensity surface haze region was observed, the surface of the wafer was uniform, and the surface haze value was 0.041 ppm. Thus, the wafers actually had acceptable surface haze properties.

Comparing FIG. 12 with FIG. 13 , it can be seen that the surface haze distribution with “high” intensity in the central region of the wafer as shown in FIG. 13 is actually a false result due to the photoluminescence of the wafer material. In contrast, after using the optical filter module of the present invention, a more accurate surface haze distribution map (FIG. 12) and a more accurate surface haze value could be obtained by effectively removing the emission signal of the wafer.

Similar results can be obtained when the optical filter module used herein is optionally a band pass filter (or else a filter coating, or a combination thereof) with a center wavelength of 473 nm.

Example 6

A 3-inch N-type InP (sulfur-doped) wafer was subjected to surface haze inspection. After being cleaned and dried, the wafer was further processed in the following steps:

1. Preliminary inspection

The cleaned wafers were inspected with the help of a high intensity light source (purchased from Yamada Optics, Japan). The luminance was 400,000 lx or more. The process and criteria of light-assisted inspection were identical to those described in Example 1. Wafers that passed preliminary inspection were used for surface haze inspection.

2. Surface Haze Inspection

A LIGHTSpEED inspection system under the 4See series of UnitySC company (France) was used.

a. Wafers that passed preliminary inspection were placed on a wafer holder (ie, wafer electrostatic chuck) of the inspection system. A blue laser with a wavelength of 473 nm was used as the incident light.

b. The optical filter module was selected in the following way: the wafer to be inspected was made of an InP material with a bandgap of 1.35 eV, so the photoluminescence wavelength of the material was calculated to be: λ _em = 1240 / 1.35 = 918 nm . Therefore, an optical filter module capable of filtering an optical signal of a wavelength of 918 nm --- a low-pass filter having a cut-off wavelength of less than 918 nm can be selected. Specifically, in this embodiment, a low-pass filter having a cut-off wavelength of 830-1200 nm and a transmittance band having a transmittance of 96% was used.

c. Signal Inspection and Analysis

An appropriate optical filter module was selected and configured in front of the signal inspection unit (ie, Si-detector) in the traveling direction of the optical signal to be detected. Then, the wafer was scanned with the laser scanning unit, the scattered light signal passing through the optical filter module was inspected by the Si-detector, and the detected signal data was analyzed by the data analysis unit (with built-in test software). The results obtained after the surface haze test are shown in FIG. 14 .

When the optical filter module was not used, the same wafer that passed the preliminary inspection was subjected to the surface haze inspection under the same conditions. The results are shown in FIG. 15 .

15 shows the surface haze of an N-type InP wafer detected without using an optical filter module. As shown in FIG. 15, a high surface haze value of 1.919 ppm was observed in the central region of the wafer. As is generally accepted in the art, when an InP-based wafer has a surface haze intensity value of less than 0.150 ppm, it is considered to have passed the surface haze test. Therefore, based on the inspection results, the wafer was considered to have unacceptable surface haze characteristics.

14 shows the surface haze of an N-type InP wafer detected using the optical filter module of the present invention. As shown in FIG. 14, no high intensity surface haze region was observed, the wafer had a uniform surface, and the surface haze value was 0.019 ppm. Thus, the wafers actually had acceptable surface haze properties.

Comparing FIG. 14 with FIG. 15 , it can be seen that the surface haze distribution with “high” intensity in the central region of the wafer as shown in FIG. 15 is actually a false result due to the photoluminescence of the wafer material. In contrast, after using the optical filter module of the present invention, a more accurate surface haze distribution map (FIG. 14) and a more accurate surface haze value could be obtained by effectively removing the emission signal of the wafer.

Similar results can be obtained when the optical filter module used herein is optionally a band pass filter (or alternatively a filter coating, or a combination thereof) with a center wavelength of 473 nm.

Example 7

A 3-inch N-type InP (sulfur-doped) wafer was subjected to surface haze inspection. After being cleaned and dried, the wafer was further processed in the following steps:

1. Preliminary inspection

The cleaned wafers were inspected with the help of a high intensity light source (purchased from Yamada Optics, Japan). The luminance was 400,000 lx or more. The process and criteria of light-assisted inspection were identical to those described in Example 1. Wafers that passed preliminary inspection were used for surface haze inspection.

2. Surface Haze Inspection

A LIGHTSpEED inspection system under the 4See series of UnitySC company (France) was used.

a. A wafer that passed preliminary inspection was placed on a wafer holder (ie, wafer electrostatic chuck) of the inspection system. A blue laser with a wavelength of 473 nm was used as the incident light.

b. The optical filter module was selected in the following way: the wafer to be inspected was made of InP material with a bandgap of 1.35 eV, so the photoluminescence wavelength of the material was calculated to be: λ _em = 1240 / 1.35 = 918 nm . Therefore, an optical filter module capable of filtering an optical signal of a wavelength of 918 nm --- a low-pass filter having a cut-off wavelength of less than 918 nm can be selected. Specifically, in this embodiment, a low-pass filter having a cut-off wavelength of 860-1300 nm and a pass band transmittance of 90% was used.

c. Signal Inspection and Analysis

A suitable optical filter module was selected and configured in front of the signal inspection unit (i.e. Si-detector) in the direction of propagation of the optical signal to be detected. Then, the wafer was scanned with the laser scanning unit, the scattered light signal passing through the optical filter module was inspected by the Si-detector, and the detected signal data was analyzed by the data analysis unit (with built-in test software). The results obtained after the surface haze test are shown in FIG. 16 .

When the optical filter module was not used, the same wafer that passed the preliminary inspection was subjected to the surface haze inspection under the same conditions. The result is shown in FIG. 17 .

17 shows the surface haze of an N-type InP wafer detected without using an optical filter module. As shown in FIG. 17, a high surface haze value of 1.719 ppm was observed in the central region of the wafer. As is generally accepted in the art, when an InP-based wafer has a surface haze intensity value of less than 0.150 ppm, it is considered to have passed the surface haze test. Therefore, based on the inspection results, the wafer was considered to have unacceptable surface haze characteristics.

16 shows the surface haze of an N-type InP wafer detected using the optical filter module of the present invention. As shown in FIG. 16, no high intensity surface haze region was observed, the wafer had a uniform surface, and the surface haze value was 0.027 ppm. Thus, the wafers actually had acceptable surface haze properties.

Comparing FIG. 16 with FIG. 17 , it can be seen that the surface haze distribution with “high” intensity in the central region of the wafer as shown in FIG. 17 is actually a false result because of the photoluminescence of the wafer material. In contrast, after using the optical filter module of the present invention, a more accurate surface haze distribution map (FIG. 16) and a more accurate surface haze value could be obtained by effectively removing the emission signal of the wafer.

Similar results can be obtained when the optical filter module used here is optionally a bandpass filter (or alternatively a filter coating, or a combination thereof) with a central wavelength of 473 nm.

Example 8

A 3-inch N-type InP (sulfur-doped) wafer was subjected to surface haze inspection. After being cleaned and dried, the wafer was further processed in the following steps:

1. Preliminary inspection

The cleaned wafers were inspected with the aid of a high intensity light source (purchased from Yamada Optics, Japan). The luminance was 400,000 lx or more. The process and criteria of light-assisted inspection were identical to those described in Example 1. Wafers that passed preliminary inspection were used for surface haze inspection.

2. Surface Haze Inspection

A LIGHTSpEED inspection system under the 4See series of UnitySC company (France) was used.

a. Wafers that passed preliminary inspection were placed on a wafer holder (ie, wafer electrostatic chuck) of the inspection system. A blue laser with a wavelength of 473 nm was used as the incident light.

b. The optical filter module was selected in the following way: the wafer to be inspected was made of InP material with a bandgap of 1.35 eV, so the photoluminescence wavelength of the material was calculated to be: λ _em = 1240 / 1.35 = 918 nm . Therefore, an optical filter module capable of filtering an optical signal of a wavelength of 918 nm --- a low-pass filter having a cut-off wavelength of less than 918 nm can be selected. Specifically, in this embodiment, a bandpass filter with cut-off wavelengths of <460 nm and >485 nm, and transmittance in the pass band of 460-485 nm (the transmittance of a wavelength of 473 nm is 100%) was used.

c. Signal Inspection and Analysis

An appropriate optical filter module was selected and configured in front of the signal inspection unit (i.e., Si-detector) in the traveling direction of the optical signal to be detected. Then, the wafer was scanned with a laser scanning unit, the scattered light signal passing through the optical filter module was inspected by a Si-detector, and the detected signal data was analyzed by a data analysis unit (including built-in test software). The results obtained after the surface haze test are shown in FIG. 18 .

When the optical filter module was not used, the same wafer that passed the preliminary inspection was subjected to the surface haze inspection under the same conditions. The result is shown in FIG. 19 .

19 shows the surface haze of an N-type InP wafer detected without using an optical filter module. As shown in FIG. 19, a high surface haze value of 2.227 ppm was observed in the central region of the wafer. As generally recognized in the prior art, when an InP-based wafer has a surface haze intensity value of less than 0.150 ppm, it was regarded as having passed the surface haze test. Therefore, based on the above inspection results, the wafer was considered to have unacceptable surface haze characteristics.

18 shows the surface haze of an N-type InP wafer detected using the optical filter module of the present invention. As shown in FIG. 18, no high intensity surface haze region was observed, the wafer had a uniform surface, and the surface haze value was 0.002 ppm. Thus, the wafers actually had acceptable surface haze properties.

Comparing FIG. 18 with FIG. 19 , it can be seen that the surface haze distribution with “high” intensity in the central region of the wafer as shown in FIG. 19 is actually a false result due to the photoluminescence of the wafer material. In contrast, after using the optical filter module of the present invention, a more accurate surface haze distribution map (FIG. 18) and a more accurate surface haze value could be obtained by effectively removing the emission signal of the wafer.

Similar results can be obtained when the optical filter module used herein is optionally a low pass filter (or otherwise a filter coating, or combination thereof) with a cutoff wavelength <918 nm.

Claims (12)

A method for detecting the surface haze of a material, comprising:
- optionally a preliminary inspection performed on the material to identify that the material is free from visible surface defects; and
- surface haze inspection to detect the surface haze of the material;
wherein an optical filter module is configured in a surface haze inspection setup to filter the photoluminescence signal of the material in an optical path to the detector to avoid the photoluminescence signal being detected by the detector. 2. The method of claim 1, wherein the surface haze inspection comprises irradiating the material with incident light, wherein the incident light is a laser of any wavelength, preferably

a wavelength of 660 nm, more preferably

, which may be a one-wavelength laser with a wavelength of 490 nm. 3. The method according to any one of claims 1 to 2, wherein the filtering is such that light having a wavelength smaller than the photoluminescence wavelength, preferably light having a wavelength not greater than the photoluminescence wavelength minus 20 nm is used in the signal detection. How to make it detectable. The method according to any one of claims 1 to 3, wherein the filtering is within the range of the incident light wavelength ± 20 nm, preferably within the range of the incident light wavelength ± 10 nm, more preferably of the same wavelength as the incident light wavelength. wherein light is to be detected in the signal detection. 5. The method according to any one of claims 1 to 4, wherein the material is any material having a smooth surface; Preferably, the material is a semiconductor material, glass or ceramic; More preferably, the material is a semiconductor wafer; Even more preferably, the semiconductor wafer has a bandgap of 1.12 to 1.53 eV, preferably 1.35 to 1.43 eV. 6. The method according to claim 5, wherein the semiconductor wafer is selected from compound semiconductor wafers, preferably direct bandgap semiconductor wafers, more preferably InP wafers or GaAs wafers. In a setup for detecting the surface haze of a material,
a material-loading unit including a sample holder for holding the material;
a laser-scanning unit including a laser source for emitting incident light; Preferably, the incident light is a laser of any wavelength, preferably

660 nm, more preferably

the laser scanning unit, which may be a one-wavelength laser with a wavelength of 490 nm;
detector; a detector that responds to an optical signal preferably having a wavelength of 280 to 1100 nm; a signal inspection unit comprising a detector, which is preferably a visible light detector, more preferably a Si-detector or an integral detector; and
a data analysis unit including software for analyzing the signal detected by the signal inspection unit;
The setup for detecting the surface haze of the material further includes an optical filter module for filtering a photoluminescence signal of the material; wherein the optical filter module is configured in front of the detector in a propagation direction of an optical signal to be detected. The setup according to claim 7, wherein the optical filter module includes an optical member capable of selectively transmitting light having a wavelength less than the photoluminescence wavelength, preferably less than or equal to the photoluminescence wavelength minus 20 nm. The optical filter module according to claim 7 , wherein the optical filter module can selectively transmit light having an incident light wavelength of ±20 nm, preferably a wavelength of an incident light of ±10 nm, and more preferably having the same wavelength as the incident light. A set-up, including an optical member located there. 10. The method according to any one of claims 7 to 9, wherein the optical filter module is selected from the group consisting of filters, filter coatings and combinations thereof, preferably low pass filters, band pass filters, low pass filter coatings. , band pass filter coatings, and combinations thereof, preferably, the optical filter module comprises a band pass filter, a band pass filter coating, or a combination thereof, preferably, the optical filter module comprises A setup, which can be an individual module, or a filter coating on the surface of the light detector, or a combination thereof. 11. Setup according to any one of claims 7 to 10, wherein the optical filter module has a signal light transmittance > 50%, preferably > 95%, more preferably > 99%. 12. The method according to any one of claims 7 to 11, wherein the setup for detecting the surface haze of a material is used to detect any material having a smooth surface; Preferably, the material is a semiconductor material, glass or ceramic; More preferably, the material is a semiconductor wafer; More preferably, the semiconductor wafer is a wafer made of a semiconductor material having a band gap of 1.12 to 1.53 eV, preferably 1.35 to 1.43 eV; preferably a wafer of a monoatomic semiconductor or a compound semiconductor; Preferably, the setup is a wafer of direct bandgap semiconductor material, more preferably a wafer of InP or GaAs.

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